The Compact Linear Collider (CLIC) is a future electron–positron collider that will allow measurements of the trilinear Higgs self-coupling in double Higgs boson events produced at its high-energy ...stages with collision energies from
s
= 1.4 to 3 TeV. The sensitivity to the Higgs self-coupling is driven by the measurements of the cross section and the invariant mass distribution of the Higgs-boson pair in the W-boson fusion process,
e
+
e
-
→
HH
ν
ν
¯
. It is enhanced by including the cross-section measurement of ZHH production at 1.4 TeV. The expected sensitivity of CLIC for Higgs pair production through W-boson fusion is studied for the decay channels
b
b
¯
b
b
¯
and
b
b
¯
W
W
∗
using full detector simulation including all relevant backgrounds at
s
= 1.4 TeV with an integrated luminosity of
L
= 2.5 ab
-
1
and at
s
= 3 TeV with
L
= 5 ab
-
1
. Combining
e
+
e
-
→
HH
ν
ν
¯
and ZHH cross-section measurements at 1.4 TeV with differential measurements in
e
+
e
-
→
HH
ν
ν
¯
events at 3 TeV, CLIC will be able to measure the trilinear Higgs self-coupling with a relative uncertainty of
-
8
%
and
+
11
%
at 68% C.L., assuming the Standard Model. In addition, prospects for simultaneous constraints on the trilinear Higgs self-coupling and the Higgs-gauge coupling HHWW are derived based on the
HH
ν
ν
¯
measurement.
A
bstract
We estimate the possible accuracies of measurements at the proposed CLIC
e
+
e
−
collider of Higgs and
W
+
W
−
production at centre-of-mass energies up to 3 TeV, incorporating also ...Higgsstrahlung projections at higher energies that had not been consid-ered previously, and use them to explore the prospective CLIC sensitivities to decoupled new physics. We present the resulting constraints on the Wilson coefficients of dimension-6 operators in a model-independent approach based on the Standard Model effective field theory (SM EFT). The higher centre-of-mass energy of CLIC, compared to other projects such as the ILC and CEPC, gives it greater sensitivity to the coefficients of some of the operators we study. We find that CLIC Higgs measurements may be sensitive to new physics scales
Λ
=
O
10
TeV for individual operators, reduced to
O
1
TeV sensitivity for a global fit marginalising over the coefficients of all contributing operators. We give some examples of the corresponding prospective constraints on specific scenarios for physics beyond the SM, including stop quarks and the dilaton/radion.
Test beam measurements at the test beam facilities of DESY have been conducted to characterise the performance of the EUDET-type beam telescopes originally developed within the EUDET project. The ...beam telescopes are equipped with six sensor planes using MIMOSA 26 monolithic active pixel devices. A programmable Trigger Logic Unit provides trigger logic and time stamp information on particle passage. Both data acquisition framework and offline reconstruction software packages are available. User devices are easily integrable into the data acquisition framework via predefined interfaces.
The biased residual distribution is studied as a function of the beam energy, plane spacing and sensor threshold. Its standard deviation at the two centre pixel planes using all six planes for tracking in a 6 GeV electron/positron-beam is measured to be (2.88 ± 0.08) µm. Iterative track fits using the formalism of General Broken Lines are performed to estimate the intrinsic resolution of the individual pixel planes. The mean intrinsic resolution over the six sensors used is found to be (3.24 ± 0.09) µm. With a 5 GeV electron/positron beam, the track resolution halfway between the two inner pixel planes using an equidistant plane spacing of 20 mm is estimated to (1.83 ± 0.03) µm assuming the measured intrinsic resolution. Towards lower beam energies the track resolution deteriorates due to increasing multiple scattering. Threshold studies show an optimal working point of the MIMOSA 26 sensors at a sensor threshold of between five and six times their RMS noise. Measurements at different plane spacings are used to calibrate the amount of multiple scattering in the material traversed and allow for corrections to the predicted angular scattering for electron beams.
We study the sensitivity of possible CLIC and FCC-ee measurements of light-by-light scattering to old and new physics, including the Heisenberg-Euler Lagrangian in the Standard Model with possible ...contributions from loops of additional charged particles or magnetic monopoles, the Born-Infeld extension of QED, and effective dimension-8 operators involving four electromagnetic field strengths as could appear in the Standard Model Effective Field Theory. We find that FCC-ee measurements at 365 GeV and CLIC measurements at 350 GeV would be sensitive to new physics scales of half a TeV in the dimension-8 operator coefficients, and that CLIC measurements at 1.4 TeV or 3 TeV would be sensitive to new physics scales Formula omitted TeV or 5 TeV at 95% CL, corresponding to probing loops of new particles with masses up to Formula omitted TeV for large charges and/or multiple species. Within Born-Infeld theory, the Formula omitted CL sensitivities would range from Formula omitted GeV to 1.3 or 2.8 TeV for the high-energy CLIC options. Measurements of light-by-light scattering would not exclude monopole production at FCC-hh, except in the context of Born-Infeld theory.
Light-by-light scattering at future e+e- colliders Ellis, John; Mavromatos, Nick E.; Roloff, Philipp ...
European physical journal. C, Particles and fields,
07/2022, Letnik:
82, Številka:
7
Journal Article
Recenzirano
Odprti dostop
We study the sensitivity of possible CLIC and FCC-ee measurements of light-by-light scattering to old and new physics, including the Heisenberg–Euler Lagrangian in the Standard Model with possible ...contributions from loops of additional charged particles or magnetic monopoles, the Born–Infeld extension of QED, and effective dimension-8 operators involving four electromagnetic field strengths as could appear in the Standard Model Effective Field Theory. We find that FCC-ee measurements at 365 GeV and CLIC measurements at 350 GeV would be sensitive to new physics scales of half a TeV in the dimension-8 operator coefficients, and that CLIC measurements at 1.4 TeV or 3 TeV would be sensitive to new physics scales
∼
2
TeV or 5 TeV at 95% CL, corresponding to probing loops of new particles with masses up to
∼
3.7
TeV for large charges and/or multiple species. Within Born–Infeld theory, the
95
%
CL sensitivities would range from
∼
300
GeV to 1.3 or 2.8 TeV for the high-energy CLIC options. Measurements of light-by-light scattering would not exclude monopole production at FCC-hh, except in the context of Born–Infeld theory.
In this paper we study the performance in
e
+
e
-
collisions of classical
e
+
e
-
jet reconstruction algorithms, longitudinally invariant algorithms and the recently proposed Valencia algorithm. The ...study includes a comparison of perturbative and non-perturbative jet energy corrections and the response under realistic background conditions. Several algorithms are benchmarked with a detailed detector simulation at
s
=
3
TeV. We find that the classical
e
+
e
-
algorithms, with or without beam jets, have the best response, but they are inadequate in environments with non-negligible background. The Valencia algorithm and longitudinally invariant
k
t
algorithms have a much more robust performance, with a slight advantage for the former.
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